1. Field of the Invention
The present invention relates in general to a contact-making apparatus for making contact with circuit units which are to be tested in a tester and which can be present on a wafer. The invention relates in particular to a self-planarizing test module device and a corresponding contact-making method.
In order to test circuit units to be tested, it is necessary for contact to be made between the circuit units under test and the tester, in which test sequences, test procedures and/or test programs are provided. Here, making contact between the circuit unit to be tested and the tester represents a particularly critical problem, since any error when making contact with the circuit unit to be tested can lead to an increase in rejects. In order to make contact between circuit units to be tested and the tester, it is necessary to provide a printed circuit board device that has electrical connections to the tester.
A conventional contact-making apparatus for making contact with circuit units to be tested in a tester is illustrated in FIG. 4. A printed circuit board device 100 has electrical connections to the tester. A test module device 101 (also designated a probe head) has a contact-making device 204, with which an electrical connection is produced between the test module device 101 and the printed circuit board device 100. In FIG. 4, contact-making elements of the cantilever type are illustrated on the underside of the test module device 101. The contact-making elements are used to make contact between the test module device 101 and the circuit unit to be tested. The circuit unit to be tested can be, for example, a chip disposed on a wafer. Contact with the circuit unit to be tested is thus made by pressing the circuit unit (or the wafer) to be tested against the contact-making elements fitted to the underside of the test module device 101. Compressing the printed circuit board device 100 onto the circuit unit to be tested thus produces contact. An electrical connection between the test module device 101 and the printed circuit board device 100 is provided by the contact-making device 204 (also designated an “interposer”).
In order to make reliable contact between the test module device 101 and the circuit unit to be tested, it is important that the surface of the test module device 101 which faces the circuit unit to be tested is substantially parallel to the wafer surface on which the circuit unit to be tested is disposed. In order to set the test module device 101, the conventional contact-making apparatus has at least one adjusting device 201. The contact-making apparatus according to the prior art preferably has at least three adjusting devices 201. In the example illustrated in FIG. 4, an adjusting device 201 has adjusting pins 202 and adjusting nuts 203. However, adjusting-the test module device 101 with respect to the printed circuit board device 100 is disadvantageously extremely time-consuming and costly.
In addition, the test module device 101 is deformed in an inexpedient manner as a result of setting the adjusting nuts 203 on the adjusting pins 202. Setting plane parallelism between the test module device 101 and the wafer with the circuit units to be tested is thus extremely difficult. Inexpediently, it is necessary for the conventional contact-making apparatus to be monitored and corrected continuously with respect to planarity and/or tilting of the test module device 101 with respect to the wafer surface. The measuring devices for monitoring planarity and/or tilting of the test module device 101 with respect to the wafer surface, that is to say what are known as test module analyzers, are extremely complicated and costly. Furthermore, it is disadvantageous that a check of this type is very time-consuming.
In particular, adjusting the test module device 101 using the adjusting pins 202 and corresponding adjusting nuts 203 is very cumbersome and requires special knowledge, so that an adjustment of this type for carrying out mass-production tests of circuit units to be tested can be carried out only with difficulty or even not at all.